1 TDT4250 - Modeling of Information Systems, Autumn 2006 Model-driven development (MDA), Software...

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TDT4250 - Modeling of Information Systems, Autumn 2006

Model-driven development (MDA), Software Oriented Architecture (SOA) and semantic web

(exemplified by WSMO)

Draft of presentation

John Krogstie

Professor, IDI, NTNU

Senior Researcher, SINTEF ICT

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Overview of lectures today and Wednesday

Overview on SOA and MDA / MDD, based on material produced in the Athena EU-project

More details based on the articles today

Articles A14 White, S. A. Introduction to BPMN A15. Pasley

, J. How BPEL and SOA is changing web services development, IEEE Internet computing May-June 2005

A16. de Bruijn, J, Fensel, D., Keller, U. and Lara, R. Using the web-service modelling ontology to enable semantic e-business, Communication of ACM Dec 2005

A17. France, R.B., Gosh, S. Dinh-Trong, T, and Solberg, A. Model-driven development using UML2.0: Promises and Pitfalls, IEEE Computer February 2006

A18. Jones, V., Rensik, A. and Briksma, E. Modelling mobile health systems: an application of augmented MDA for the extended healthcare enterprise

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BPMN – based on a presentation by Steven White

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Business process management (BPM) services

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Model-driven development (MDD)

CIMCIM

BusinessContextModels

PIMPIM

Modeltrans-

formation

SoftwareSpecification

Models

PSMPSM

SoftwareRealisation

Models

Modeltrans-

formation

Model-driven approach to system engineering where models are used in• understanding• design• construction• deployment• operation• maintenance• modification

Model transformation tools and services are used to align the different models.

Business-driven approach to system engineering where models are refined from business needs to software solutions• Computation independent model (CIM) capturing business context and business requirements• Platform independent model (PIM) focusing on software services independent of IT technology• Platform specific model (PSM) focusing on the IT technology realisation of the software services

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Current MDA Architecture

CIMmodels

PIMSystemmodels

PSMSystemmodels

System

QVT

QVT

MOF2Txt

Enterprisemodeling

expert

Systemmodeling

expert

Systemrealisationinstallation

expert

UML2.0

MOF2.0

XMI2.0

Ontology

ODM

BPDM

OrgMM

BSVR

OWL

ATLMOFScriptEMF Java APIMTF (IBM)

QVT(MOF2Txt)

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A17. France, R.B., Gosh, S. Dinh-Trong, T, and Solberg, A. Model-driven development using UML2.0: Promises and Pitfalls, IEEE Computer February 2006

Navigating the metamuddle

Arnor Solberg, Robert France, Raghu Reddy

Colorado State University and SINTEF Norway

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Claim

The complexity of the current UML 2 metamodel make the understanding, using, extending and evolving the metamodel difficult

1000 + pages specification

large and fragmented

Available as a model in Rational Rose

Only for visualization, no manipulation features available (e.g. queries)

Poorly documented

This is a risk factor for MDD in general and MDA in particular!

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This is a problem since..

MDD require development teams to understand, use and extend metamodels

Configuring and tailoring MDD frameworks need to be done for each domain and even System Family to be able to succeed with MDD.

Defining domain specific modeling concepts (for example by means of profiles), specification of metamodel mappings (transformations) and model composition will be main tasks

Task for Domain and System Family architects. No out of the box tools to buy from vendors. Tailoring is needed

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Conceptual transformation model

Source(e.g., UML domain/PF

subset/profile)

<<metamodel>>

Source2Target Scheme

<<transformation>>

<<Model instance>>Source

implementation

<<source>>

Target(e.g. CORBA UML profile)

<<metamodel>>

<<target>>

<<source>> <<target>>

<<conforms_to>>

Transformation(e.g. MOF2.0 QVT)

<<metamodel>>

<<Model instance>>Target

Transformation

<<conforms_to>><<conforms_to>>

<<conforms_to>>

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Good news and bad news

Good news is

In practice only part of the UML is used

Subset of diagrams

Subset of concepts

-> Should not need to have the full knowledge of the UML metamodel to use “your” part of UML

Bad news

Need to manually navigate the metamuddle to extract the concepts you want to use

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A glimpse into the story

Illustrative Example

Mapping of Simple UML interactions models (e.g. to UML profile for CORBA)

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Simple metamodel for UML interactions

Want to extract the Lifeline and Message concepts and their relationships.

These are core concepts for modeling interactions so you would expect to find their properties and relationships quite easily in the standard

Examination of the Interactions section in the UML specification, reveals that the information required in this simple view is not available in one place in the metamodel.

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Lifeline fragment (no obvious relation to Message)

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Messagefragment(no lifeline)

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Problems of UML

Large and complex Specification fragmented Leads to accidental complexity

As opposed to inherent problem complexity

This is a risk factor for the MDA vision!

Furthermore how do you evolve the UML model in a consistent manner?

How can one be sure that required changes are incorporated consistently across the metamodel?

How can one determine the impact that a change will have on other metamodel elements?

In particular, how can one ensure that the changes do not result in a metamodel that defines inconsistent or nonsensical language constructs?

It will be extremely difficult to evolve the UML 2.0 metamodel to reflect changes in the UML standard using only manual techniques.

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Suggestions

Need user oriented views into the metamuddle

At least a simple view of the metamodel for each diagram type that describes only the concepts and relationships that appears in the diagram

Use aspect oriented techniques e.g. to Provide views of the set of diagram types that only contain concepts that are

visible in the diagrams (abstract concepts such as NamedElement will not appear in such diagrams, but derived properties will)

Define aspects presenting views of abstract concepts reflecting language and UML-specific concerns such as name space management, element typing, connectivity of elements, and execution semantics.

Make it easier to evolve (e.g., change aspects, new aspects)

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Tool support

At least

Tool that allows developers to query the metamodel, to extract views of the metamodel

E.g., get all relationships and properties of a metamodel concept

Including the derived ones

Some tools provide some of this capability already

Xactium

Megamodelling, ATL (Jean Bezivin)

Better

Tool that take UML models as input and automatically extract the metamodel for this set of input models

Implicit model checking (compliance checking)

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Conclusion

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Questions

How do we eliminate accidental complexity such as the one illustrated in this presentation

Other examples exists, e.g., the QVT specification

Is this a unavoidable for new, immature fields?

Problem is to include the users in the evolution of the field when there is too much accidental complexity involved when using it

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Conclusion and further work

MDD framework that facilitates: Horizontal separation

Handling crosscutting features distributed across a model

Emphasis on QoS during model specification and transformation

Simplify transformations

Vertical separation of concerns Abstractions e.g., to manage diversity and evolution of platforms

Future work More case studies

Different platforms, Repository of models and mappings of common middleware concerns

Profile for specifying model weaving

Usage of framework for adaptive systems and adaptive middleware (E.g., Madam middleware)

Increase flexibility and ease evolution of adaptive systems

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WSMO overviewAs basis for A16. de Bruijn, J, Fensel

, D., Keller, U. and Lara, R. Using the web-service modelling ontology to enable semantic e-business, Communication of ACM Dec 2005

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Contents

Mission of WSMO

WSMO Standard

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Mission of WSMO

Web Service Modeling Ontology

WSMO is a conceptual model for relevant aspects related to Semantic Web Services

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WSMO Standard

Provide the formal

semantics of the

information used by

all other components

Semantic description of Web Services: - Capability (functional)- Interface (usage)

Specify objectives that a client may have

when consulting a Web Service

Connectors between components with mediation facilities (de-coupling)

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WSMO Standard - Ontologies

Non functional properties Used mediators

Importing / re-using ontologies as modular approach for ontology design. OO Mediators:

handles all ontology management issues (access, namespaces, etc.) ontology integration (merging / alignment)

=> Modularization & De-coupling Axioms

The set of axioms that belong to the represented ontology. Concepts

The set of concepts that belong to the represented ontology. Relations

The set of relations that belong to the represented ontology. Instances

The set of instances that belong to the represented ontology.

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WSMO Standard - Goals

Non functional properties

Used mediators

import ontologies using OO Mediators.

GG Mediator: Goal definition by reusing an already existing goal.

Post-conditions

describe the state of the information space that is desired.

Effects

Effects describe the state of the world that is desired.

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WSMO Standard - Mediators

Principle of De-coupling for handling complexity & heterogeneity

=> Mediators: WSMO components are never allowed to touch each other without a mediator in-between.

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Source component

the connected entity / entities

Target component

the connecting entity / entities

Mediation Service

links to Mediation Facility needed to resolve heterogeneity

Reduction describes the differences between the connected entities

only in WG or GG

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WSMO Standard – Web Service


Used mediators OO Mediators for importing ontologies as the

formalized

terminology for describing the Web Service

Capability

functional description (WHAT), 1:1

Interfaces

description of usability & composition (HOW), 1:n

Semantic Description of Web Services to allow

(semi-)automated usage of Web Services

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WSMO Standard – Capability


OO Mediator: importing ontologies as terminology definition WG Mediator: link to a Goal that is solved by the Web Service

Pre-conditions what a web service expects in order to be able to

provide its service, i.e. conditions over the input Assumptions

Conditions on the state of the world that has to hold before

the Web Service can be executed Post-conditions

describes the computational result in relation to the input

of the Web Service, and conditions on it Effects

Conditions on the state of the world that hold after execution of the

Web Service (i.e. changes in the state of the world)

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WSMO Standard – Interfaces

describes how the functionality of the service can be achieved provides a twofold view on the operationalization of the Web

Service:

1. Choreography defines how to communicate with the web service in order to consume its functionality.

2. Orchestration defines how the overall functionality is achieved by the cooperation of more elementary service providers.

Choreography & Orchestration = different decompositions of process/capabilities to the top (service requester) and to the bottom (other service providers).

This distinction reflects the difference between communication and cooperation.

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OO Mediators for importing ontologies as terminology definitions

Choreography provides the necessary information for the user to communicate with the web

service. described by an instantiated Message Exchange Pattern

Orchestration describes a service makes use of other web service or goals in order to achieve it's

capability. specifies the composition of Web Services used by a Web Service described as an instantiated Problem Solving Pattern.

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WSMO Standard – Language

F-Logic combines the advantages of conceptual high-level approaches typical for frame-based language and the expressiveness, the compact syntax, and the well defined semantics from logics.

it provides a standard model theory

it is a full first order logic language

it provides second order syntax while staying in the first order logic semantics

it has a minimal model semantics

implemented inference engines are already available.

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WSMO Working draftsat: http://www.wsmo.org/2004/

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Model-driven development (MDA), Software Oriented Architecture (SOA) and semantic web

(exemplified by WSMO)

John Krogstie

Professor, IDI, NTNU

Senior Researcher, SINTEF ICT

1 TDT4250 - Modeling of Information Systems, Autumn 2006 Model-driven development (MDA), Software...

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